YM2310D Oil Pressure LIght

[tonyg2160]

Just finished repainting EVERYTHING. Removed a lot of stuff..masked a lot of stuff. Before I started the project I could press the "Check" button and all 4 of the idiot lights on the gauge panel would light up. Now...my oil pressure light won't. I checked the bulb and it's good. I think I recall it lighting up briefly when starting now (I've only started it once since re-assembly). At any rate, I figure that maybe I need to check and re-seat the connector at the sending unit. Question is...where is the sending unit for the oil pressure light? Is there anything else that I should check?

 

[normde2001]

Always near the oil filter, can't miss it, a screw-in thingy with a wire attached.
.

 

[California]

Is that switch like the earlier single-wire ones that make a connection to ground when there is no oil pressure, then go open (no connection) when pressurized?

 

[HoyeTractor]

Is that switch like the earlier single-wire ones that make a connection to ground when there is no oil pressure, then go open (no connection) when pressurized?

It is, yes.

 

[tonyg2160]

It is, yes.

So...the sending unit has one wire that goes to ground? No pressure...goes to ground...light comes on. Pressure = no ground..no light. NO GROUND wire connection would ALSO = no light. (?) So, most likely I've just got a bad connection at the sending unit?

 

[California]

I think I defined that backward. I recall tearing off that sender wire while rasseling brush.

That brought the light ON when the signal current no longer arrived at the switch.



In contrast the temp sender light is off until you ground its signal wire (or overheat).

 

[HoyeTractor]

You had it right the first time. The oil pressure switch just completes the ground to the warning light when there is low/no oil pressure. To test the light and the wiring you can unplug that wire and touch it to bare metal on the engine. Same for the temp light.

The attached section is saying do this test if the oil warning light does not come on with the engine off.

 

[tonyg2160]

Well...It's "fixed", but now I'm confused...I think :confused2:. Apparently, the connection on the end of the sending unit was slightly corroded...just enough that in my messing around with it during painting I had caused it to lose connection. I jiggled it around and now it's "fixed". The way it was acting before was: When pressing the "check" button...no light, when starting-no light, when running-no light. The key here is the "check" button-no light. My understanding of the system is that the switch (sending unit) is "normally closed" - with a completed circuit (and light) under low/no pressure conditions. Once the engine is running with sufficient oil pressure, the "switch" is opened, causing the light to "turn off". The corroded connection effectively "removed" the signal from the system so - no light...regardless of "switch position". Ultimately...I think the "check" button is more important than people give credit for. If you press the check button and don't get an oil pressure light you either have a bad bulb, or a bad connection. I don't think this in any way "checks" the sending unit...just the bulb circuit from the sending unit. Actually a pretty simple system, but I think nowadays people think buttons and such "do more" than they do on these older, simpler systems. Nevertheless...the "check button" is an important button, but it just checks the circuit.

 

[HoyeTractor]

I might be wrong but I don't think the check button does anything to the oil light on the 2310. Unless I'm interpreting the wiring diagram wrong, I think it only checks the temp light & low coolant lights (both lights would be difficult to check without this feature). Some other models like the YM1610 show the 'check light' diodes going to the oil pressure light as well but not the 2310. The oil pressure light & circuit can be 'tested' by just turning the key on. Does the check button light up your oil light now that you fixed the connection?

 

[tonyg2160]

It does. When the connection was bad, only three of the four lights would glow. I knew that before, all four would glow. Now that the connection is good again, all four glow when the check button is pressed.

 

[HoyeTractor]

Now that the connection is good again, all four glow when the check button is pressed.

Interesting. Is that with the engine running? If not, the oil light would be glowing even without pushing the button.

 

[tonyg2160]

I see your point. Now I'm confused again. I'll triple check when I get home.

 

[California]

You got NO light when the wire wasn't properly connected to the sensor. ... And I can't reconcile your experience with what I saw.

On the YM240, I drove into a downed tree to pick it up and carry it away. A branch poked the sender wire, tearing it off. The oil pressure warning light came on.

I drove back to the barn with the light on, that was un-nerving even though I knew the cause.

Spliced the wire and the system went back to normal, light on only before the engine fires off and runs up the oil pressure.

 

[California]

Not on-topic but I'll post this for some future reader who searches 'Yanmar oil pressure light'.

The sender to drive the warning light seems to be universal across many Japanese cars. So long as it has BSP, British Standard Pipe thread (widely used in Japan) it will work, but don't get the very similar one with USP threads.

Long ago I posted a thread about apparent low oil pressure and someone (Norm?) suggested the sender was far more likely. When I put on a test gauge the pressure was 30~35 psi, normal, so the apparent 'low oil pressure' was in fact the failed sender. Thanks Norm.

 

[tonyg2160]

You got NO light when the wire wasn't properly connected to the sensor. ... And I can't reconcile your experience with what I saw.

On the YM240, I drove into a downed tree to pick it up and carry it away. A branch poked the sender wire, tearing it off. The oil pressure warning light came on.

I drove back to the barn with the light on, that was un-nerving even though I knew the cause.

Spliced the wire and the system went back to normal, light on only before the engine fires off and runs up the oil pressure.

If the sender "sees ground" to display a warning light, and oil pressure "opens" the switch to remove ground and turn the light off, wouldn't disconnecting the wire "remove ground" and turn the light off? After reading Aaron's post above, I believe mine is now (since re-connecting) "ON" with key on engine off, then after starting, the switch "sees" pressure and opens to turn the light off. I do think (going to double check this evening) that pressing the "check" button with engine running will turn ALL 4 warning lights on to confirm function. Maybe the 240 is "normally open" instead of "normally closed"?

 

[HoyeTractor]

On the YM240, I drove into a downed tree to pick it up and carry it away. A branch poked the sender wire, tearing it off. The oil pressure warning light came on.

I wonder if maybe the wire came loose and touched the frame or something?

From the YM240 service manual....

 

[California]

I wonder if maybe the wire came loose and touched the frame or something?

From the YM240 service manual....

View attachment 547267

I guess I have an unexplained mystery. I saw the light on steady as I drove back to the barn, over rough ground that would have jiggled an intermittent ground. My instincts were saying 'Stop and investigate the failed oil pressure, save the engine!' while I kept telling myself the light on meant nothing. Heck maybe I dreamed that the following night! essimist:

In this photo the splice is where it broke.

Also - looking for that photo I found it is in the thread where I documented my temperature readings at the head, pan, etc - for anyone interested.

Re: Low oil pressure? No, bad sender!

 

[tonyg2160]

Alright...I checked mine and Aaron is correct. When I turn the key on, the Alternator and Oil Pressure lights come on. Once engine starts and the sender see oil pressure the oil light goes off. As an aside, the alternator light doesn't go off until I get enough RPM to start charging the battery. When running, if I press the "check" button only the "battery" light and the temp lights come on.